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Full text of "IS 2858: Code of practice for roofing with mangalore tiles"

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Disclosure to Promote the Right To Information 

Whereas the Parliament of India has set out to provide a practical regime of right to 
information for citizens to secure access to information under the control of public authorities, 
in order to promote transparency and accountability in the working of every public authority, 
and whereas the attached publication of the Bureau of Indian Standards is of particular interest 
to the public, particularly disadvantaged communities and those engaged in the pursuit of 
education and knowledge, the attached public safety standard is made available to promote the 
timely dissemination of this information in an accurate manner to the public. 




Mazdoor Kisan Shakti Sangathan 
"The Right to Information, The Right to Live'' 



IS 2858 (1984) : Code of practice for roofing with mangalore 
tiles [CED 13: Building Construction Practices including 
Painting, Varnishing and Allied Finishing] 




Jawaharlal Nehru 
'Step Out From the Old to the New" 



aj^&vi iJii^s:y%K^ isb^^ni^seg 



:<>5&i| mT'5K^5?::5:^>^i»l 



K^^^iXSVCd^ 



Satyanarayan Gangaram Pitroda 
Invent a New India Using Knowledge 



Bhartrhari — Nitisatakam 
''Knowledge is such a treasure which cannot be stolen" 




^'^^^r 



k 




BLANK PAGE 



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PROTECTED BY COPYRIGHT 



13 ZS5S T9a4 

( Reaffirmed 2000 ) 

Indian Standard 

CODE OF PRACTICE FOR 
ROOFING WITH MANGALORE TILES 

( First Revision ) 



1 7UC 4iy ■ (rj+- 1 53 ■ * r 6y 00 i s 




INDIAN STANDARDS INSTIT.UTION 

MANAK BHAVAN. 9 BAHADUR SHAH ZAFAR MAKC 

tft^W DELHI 11OU02 

<^** MtfwA 1985 



IS t 2858 - 1984 

Indian Standard 

CODE OF PRACTICE FOR 
ROOFING WITH MANGALORE TILES 

( First Revision ) 



Building Construction Practices Sectional Committee, BDC 13 

Chairman 

Shbt C. p. Malik 

C-4/38, Safdarjung Development Area, 

New Delhi- 11 00 16 

Members Representing 

Shri P. D. Agarwal Public Works Department, Government of 

Uttar Pradesh, Lucknow 
Shri R. K. Mathur ( Alternate ) 
Shri D. R. Batlivala Bhabha Atomic Research Centre, Bombay 

Shri B. K. Chakraborty Housing and Urban Devrlopment Corporation Ltd, 

New Delhi 
Shri S. M. Goel ( Alternate ) 
Chief Ekgi^s^eeu ( Bldgs ) Public Works Department, Government of 

Tamil Nadu, Madras 

SrPKRiNTENDJNO ENGINEER 

( Special Buildiijg Circle ) ( Alternate ) 
Chief Engineer-cum-Audl Public Works Department, Government of Rajasthan, 

Secretary ( BR ) Jaipur 

Executive Engineer ( Alternate ) 
Chief Engineer (Training ) Central Public Works Department, New Delhi 

Superintending Engineer 
( Training ) ( Alternate ) 
Shut K. Devarajan Engineer-in-Chief s Branch, Army Headquarters, 

New Delhi 
SiiRi A. V. GoPALKiiiSHNA ( Alternate ) 
DiKECTOR, Architecture Research, Designs and Standards Organization 

( Ministary of Railways ), Lucknow 
Joint Director, Architec- 
ture ( Alternate ) 
Shri S. S. Gjll Public Works Department, Government of Punjab, 

Chandigarh 
Shri M. Kartikayan Builders' Association of India, Bombay 

Shri R. L. Kumar Institution of Surveyors, New Delhi 

Shri V. G. Patwardhan ( Alternate) 

( Continued on page 2 ) 



©Copyright 1985 

INDIAN STANDARDS INSTITUTION 

This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and 
reproduction in whole Or in part by any means except with written permission of the 
publisher shall be deemed to be an infringement of copyright under the said Act. 



lis 3 2858 - 1984 

( Continued from page 1 ) 

Members Representing 

Shri M. Z. Kubien Tata Consulting Engineers, Bombay 

Shri G. K, Majumdak Hindustan Prefab Ltd, New Delhi 

Shki H. S. Pasricha ( Alternate ) 
Shri R. C. Mangal Central Building Research Institute ( CSIR ), 

Roorkee 

Shut B. S. Sharma ( Alternate ) 
Shri B. V. B, Pai Concrete Association of India, Bombay 

Shri P. Srinivasan ( Alternate ) 
Shri P. K, Pandare State Bank of India, Bombay 

Shri K. S. Prtjthi Forest Research Institute and College, Dehra Dun 

Shri S. G. Ranadzve Indian Institute of Architects, Bombay 

Shri Rummy Shrotf ( Alternate ) 
Representative Bureau of Public Enterprises, Ministy of Finance, 

New Delhi 
Representative Central Road Research Institute, New Delhi 

Representative Life Insurance Corporation of India, Bombay 

Shri K. S. Srinivasan National Buildings Organization, New Delhi 

Deputy Director ( Alternate ) 
Shri Sushil Kumar National Buildings Construction Corporation Ltd, 

New Delhi 
Shri S. R. Tambe Public Works & Housing Department, Bombay 

Shri B. T. Unwax^la The Institution of Engineers ( India ), Calcutta 

Shri G. Venkatesulu Ministry of Shipping & Transport (Roads Wing), 

New Delhi 

Shri M. V. Sastry ( Alternate ) 
Shri G. Raman, Director General, ISI ( Ex-officio Member ) 



Director ( Civ Engg ) 



Secretary 

Shri A, K. Saini 
Assistant Director ( Giv Engg ), ISI 



Floor and Roof Construction Subcommittee, BDC 13 : II 

Convener 
Shri D. R, Batlivala Bhabha Atomic Research Centre, Bombay 

Members 

Shri S. C. Ghakrabarti Central Building Research Institute ( CSIR ), 

Roorkee 
Shri N. C. Majumdar ( Alternate ) 
Shri S. K. Chakrabarty Calcutta Metropolitan Development Authority, 

Calcutta 
Chief Engineer ( B&R ) Public Works Department, Government of Rajasthan, 

Jaipur 
Shri H. N. Saxena ( Alternate ) 
Shri K. Devarajan Engineer-in-Chief's Branch, Army Headquarters, 

New Delhi 
Maj a. K. Kadian ( Alternate ) 

( Continued on page \Q ) 



IS I 2858 - 1984 

Indian Standard 

CODE OF PRACTICE FOR 
ROOFING WITH MANGALORE TILES 

( First Revision } 



0. FOREWORD 

0.1 This Indian Standard (First Revision ) was adopted by the Indian 
Standards Institution on 28 September 1984, after the draft finahzed by 
the BuiJding Construction Practices Sectional Committee had been 
approved by the Civil Engineering Division Council. 

0.2 Mangalore tiles are machine made burnt-clay tiles widely used for 
roofing work in this country. Its design incorporates corrugation for 
drainage and also an efficient interlocking system between the tiles 
enabling them when laid to form a leak-proof layer. Depending upon 
the degree of protection needed from the roof, Mangalore tiles may be 
laid as such or with an under-layer of flat tiles or ceiling tiles, etc. A 
specific advantage of a tiled roof is the case of maintenance since any 
broken tiles can be easily replaced without much disturbance to the 
roofing as a whole. The design of the Mangalore tile takes into account 
this aspect and the tile as laid on the roof will be able to carry the weight 
of a man it is called upon to support during such repair. Though 
originally produced in areas near Mangalore, this tile is now manufac- 
tured and used in many parts of this country. For efficient performance 
of Mangalore tiled roof there are several design and constructional 
details one should take care of during laying the roof. This code is 
intended to provide guidance with regard to all these details. 

0.3 This standard was published in 1964. The revision has been under- 
taken to incorporate the necessary modifications as a result of experience 
gained during the use of this standard. The modifications include 
additional requirements for ventilating tiles and in requirements for 
fixing of valley gutter. 

0.4 The Sectional Committee responsible for the preparation of this 
standard has taken into consideration the views of producers, consumers 
and technologists and has related the standard to the manufacturing and 
trade practices followed in the country in this field. Due weightage has 
also been given to the need for international co-ordination among 
standards prevailing in different countries of the world. 



IS: 2858 -1984 

0.5 For the purpose of deciding whether a particular requirement of 
this standard is complied with, the final value, observed or calculated, 
expressing the result of a test or analysis, shall be rounded off in accord- 
ance with IS : 2-1960*. The number of significant places retained in 
the rounded off value should be the same as that of the specified value in 
the standard. 



1. SCOPE 

1.1 This standard covers roofing with Mangalore pattern tiles which 
may include the following types of work: 

a) Mangalore tiles laid directly over reepers ( see Fig. 1 ); 

b) Mangalore tiles laid with or without mortar on flat tiles, which 
are laid over reepers ( see Fig. 2 ); and 

c) Mangalore tiles laid on ceiling tiles which are laid over reepers 
{see Fig. 3 ). 

2. TERMINOLOGY 

2.1 For the purpose of this standard, the following definitions shall 
apply. 

2.1.1 Barge Board — In the case of a gable roof where there is no gable 
parapet and the roof projects beyond the gable, the barge boards are 
planks running down from the ridge to the eaves covering the outer 
most rafters. 

2.1.2 Ceiling Tile — A machine pressed tile used under the Mangalore 
tile so as to provide a surface flush with the underside of the reepers 
{see IS : 1464-19731). 

2.1.3 Collars — The structural members fixed horizontally on either 
side of the ridge so as to serve as connecting ties for the common rafters. 

2.1.4 Dormer — A vertical window or opening framed in a sloping 
roof 

2.1.5 Downpipe — Pipe which collects rain water from the roof, from 
the roof gutters, or from both and conveys it to a drain, sump or other 
point of discharge. 

2.1.6 Eaves — The lower edge of an inclined roof ( see Fig. 4 ). 



♦Rules for rounding off numerical values ( revised), 
tSpecification for clay ridge and ceiling tiles {first revision ), 



Oi 




MANGALORE TILE 



GALVANIZED WIRE FOR TYING 
DOWN TILES TO THE REEPER 



BATTEN OR REEPER 
WOODEN RAFTER 



RIOGE Tte 

EDGE BEDDING IN MORTAR 
MANGALORE TILE 



ENLARGED DETAIL AT A 

GAUGE OF TILE- 
HEAD LAP- 

GAl 
MS 

SCREW 





MANGALORE TILE 



BATTENS OR REEPERS 
WOODEN RAFTER 
TlTtNG FILLET 




-EAVES BOARD 
-EAVES GUTTER 



TYING LUG 

MS GALVANIZED 
WIRE 



WOODEN 
RAFTER 



BATTEN OR 
REEPER 



ENLARGED SECTION THROUGH TYING LUG 

(OF MANGALORE TILE) 



Fig. 1 Detail of Mangalore Tiles Laid on Reefers 



K01 



S 
S 



i 



IS s 2858 ^1994 

-MANGALORE TILES 
-MORTAR UYER 
-FLAT TILES 




RETAINING FILLETS TO 
BE USED WHEN PITCH 
IS MORE THAN 30*- 



MANGALORE TILES 



-REE PER OR BATTEN 
-WOODEN RAFTER 

ENLARGED DETAIL AT A 




OODEN RAFTER 



-REEPERS OR BATTENS 
-2.5 cm MIN THICK MORTAR LAYER 

-f LAT TILES 



Fig. 2 Detail of Mangalore Tiles Embealded in Mortar 
Over Flat Tiles 



MANGALORE TILES 



CEILING TILES 




BATTEN OR 
REEPER 



FLANGE OF 
CEILING TILE 



WOODEN RAFTER 



WALL PLATE 




ENLARGED DETAIL AT A 

Fig. 3 Mangalore Tile Laid Over Ceiling Tiles 

6 



IS»:2858-19M 



GABLE PARAPET 



RIDGE 



MORTAR 
BANDS 



BARGE 
BOARDS 



GALVAfHZED MS FLAT 
TYWG DOWN TIES 




■GABLE 



VERGE 



Fig. 4 Nomenclature of a Pitched Roof 



2.1.7 Eaves Board — A thin p]ank at the eaves covering the lower ends 
of common rafters. 

2.1.8 £% 5^^rffn^ — The bedding of the ridge tile at its two longi- 
tudinal edges over mortar layers supported on the two courses of roofing 
tiles occuring on either side. 

2.1.9 Flashing — A strip of impervious material, usually metal, used 
to exclude water from the junction between a roof covering and another 
part of the structure, 

2.i.l0 Flat Tile— A hand made or machine pressed burnt clay tile 
laid in one or more courses as an underlayer for roofing. 

2.1.11 Gable — The tringular upper part of a wall at the end of a ridge 
roof ( see Fig. 4 ). 

2.1.12 Gauge of Tile — The effective distance along the roof slope 
which is covered by the tile. 

2.1.13 Gutter — Any form of roof water channel. 

2.1.14 Hip — A salient angle formed by the intersection of two inclined 
roof surfaces ( J^^ Fig. 4 ). 



IS: 2858 -1984 

2.1.15 Lap — The distance by which one tile overlaps and adjacent 
tile. When ^measured from course over course, this will be termed as 
*head lap', and when measured edge over edge of the tile, this will be 
termed as 'side lap'. 

2.1*16 Mangalore Pattern Tile — A machine pressed roofing tile confor- 
ming to IS : 654-1972*. 

2.1.17 Pitch — The angle of inclination with the horizontal of the 
rafters or other surface on which tiles are laid. 

2.1.18 Pitched Roof — A roof the pitch of which Is greater than 10° to 
the horizontal. 

2.1.19 Rafters 

2.1.19.1 Common rafters — The structural members which form the 
principal framework for the slopes of the roof, and support the reepers 
or boarding which carry the roof covering, 

2.1.19.2 Hip rafters — The structural members of the roof at the 
intersection of two roof surfaces forming a hip. 

2.1.19.3 Jack rafter — The rafters that are shorter than the common 
rafters running from a hip to the eaves or from a ridge to the valley, and 
cut against the hip and ridge. 

2.1.19.4 Valley rafters — The structural members of the roof at the 
intersection of the two roof surfaces forming a valley, 

2.1.20 Reepers or Battens — Horizontal timber members of small section 
on which tiles are supported, 

2.1.21 Ridge — The horizontal intersection of two rising roof surfaces 
inclined in opposite directions. 

2.1.22 Ridge Piece — - The timber member underneath the ridge, to 
which the ends of common rafters are jointed ( see Fig. 1 ), 

2.1.23 Ridge Tile — A machine pressed clay roofing tile usually 
angular shaped used at the ridges and hips of roofs, and with its size 
corresponding to the size of the roofing tile ( see also 5.3 and IS ; 1464- 
19731). 

2.1.24 Roof Parapet — The part of the structure of the side walls of the 
building rising above the eave level of the roof. 



♦Specification for clay roofing tiles, Mangalore pattern ( second revision ). 
tSpecification for clay ridge and ceiling tiles {first revision ). 



18:2858-1984 

2.1.25 Tilting Fillet — A fillet or reeper fixed over the rafter on shorter 
side so as to provide an extra rise to the lower most course of the tile 
and bring its slope in conformity with the general pitch of the roof. 
Sometimes the top edge of the eaves board may itself be made to serve 
the function of the tilting fillet. 

2.1.26 Undercover — A layer of fiat tiles, ceiling tiles, bituminus felt, 
wooden boards, or corrugated sheets provided between the rafters and 
the Mangalore tile layer so as to improve functional performance of the 
roof. 

2.1.27 Valley — The re-entrant angle formed by the intersection of two 
inclined roof surfaces ( see Fig. 4 ). 

2.1.28 Verge — The edge of a roof surface finished at a gable, or the 
edge of vertical tiling at window reveals, ends of walls and dormer 
cheeks ( see Fig. 4 ). 

2.1.29 Wall Plate — A structural member resting on the wall and 
supporting the rafters with the specific object of distributing the load 
evenly over the wall. 

3. NECESSARY INFORMATION 

3.1 For efficient design and construction of the work, detailed informa- 
tion with regard to the following is necessary: 

a) Surface area to be covered; 

b) Type of supporting elements and restrictions, if any, to their 
arrangement; 

c) Treatment of junctions with walls; 

d) Provision for slope and other requirements for drainage; and 

e) Provision for fixing ridge tiles, 

3.2 All information shall be made available to those who are responsible 
for laying the roof. Necessary drawings and instructions for preparatory 
work shall be given. 

3.3 Arrangement shall be made for proper exchange of information 
between those engaged in laying and all others whose work will affect 
or will be affected. 

4. DESIGN CONSIDERATIONS 

4.1 Weather Resistance — In addition to other normal functions, the 
essential function of a tiled roof covering will be to drain away rain 



water and effectively prevent its ingress into the structure below. The 
interlocking of the tiles as well as the laying technique shall ensure that 
the joints are leak-^proof; furthermore the roof shall also have an 
effective roof drainage system which will quickly drain off the rain water. 
For this purpose, in addition to the drainage channels formed by the 
corrugations of the Mangalore tiles, a proper layout of roof gutters and 
downpipes for the roof surface as a whole will be necessary. 

Provision of an undercover for the roof will not only add insulation 
and waterproofing but will also prevent debris and insects falling from 
the roof. 

4«L1 Protection of Verges Against Wind — The verges of roof shall be 
protected against lifting by wind by provision of either bargeboard and 
filletting arrangements or a bending wall over the gable wall. Other 
constructional features regarding laying of tiles for protection at eaves 
shall be as in 9,1*1* 

4.2 Lap and Pitch — Generally the pitch of the common rafter or 
surface on which Mangalore tiles are laid shall not be less than 24° arid 
not greater than 45". Where abnormal conditions may be expected, such 
as in elevated sites or in areas of heavy rainfall, this minimum pitch may 
not ensure full protection to weather and pitch shall be suitably increased 
in which case each tile shall be screwed or tied down to the roofwork 
below. If necessary, additional protective measures such as the provision 
of an undercover of a layer of roofing felt, or a course of flat tiles with a 
mortar layer for bedding of Mangalore tiles or a ceiling boarding nailed 
to rafters shall be adopted under the roof. In the design of roofs with 
low pitches, it shall be borne in mind that each tile is tilted up at its 
lower edge by the tile below and that the pitch of the tile is less than 
that of the common rafter. 

The tiles shall be laid with both head lap and side lap as fixed by 
the design of the tile. If the head lap is not fixed by the design of the 
tile, it shall not be less than 75 mm ( see Fig. 1 ). 

4.3 Keepers -~ The spacing of rafters shall not normally exceed 600 mm 
unless the reepers are otherwise designed against sagging taking intp con- 
sideration the species of timber used and the load covering over them. The 
size of reepers, unless otherwise designed, shall normally be 50 X 25 mm 
for Mangalore tiles laid over flat tiles over reepers and 50 x 15 mm for 
Mangalore tiles over reepers or over ceiling tiles laid on reepers. 

4.3.1 Where ceiling boarding is adopted, the boarding shall not be 
less than 12 mm thick, and shall be tongued and grooved, and it shall 
be nailed to the rafters first so as to form a continuous surface from ridge 
to eave, and the reepers nailed over them. Alternatively^ the ceiling 
boarding may be fixed direct to purlins. The size of the reepers shall 

10 



IS: 2858 -1984 

not be less than 25 X 25 mm fixed at suitable distances apart to suit 
the tile spacing. The maximum spacing of the rafters shall not exceed 
750 mm. 

4*4 Aspects of Dimensional Coordination — In the design of 
pitched roof coverings the span of the roof and other details shall 
facilitate the minimum cutting of tiles during laying. Knowing the 
*gauge' of the tile, and the play that is permitted by the interlock 
between tiles and allowing suitable extra distances required near the 
eave and the ridge or hip, it is possible to adjust the length of the 
common rafter and other relevant dimensions of the roof to correspond 
to exact multiples of the gauge length of tile, and this will avoid use of 
cut tiles near the ridge. Generally a ridge tile corresponding to a 
pattern of roofing tile will have a length which covers exactly twice the 
effective width of the roofing tile. 

4.5 Strength and Stability — While considering the strength and 
stability of the roof framework supporting Mangalore tiled roof, the 
following dead loads shall be taken into account: 

Description of Roof RisejSpan Dead Mass of Roof 

Covering 
kg/m^ 

Mangalore tiles embedded in 4 to | 110 

mortar over flat tiles 

Mangalore tiles with flat tiles i to J 80 

without mortar for embedment 

, Mangalore tiles alone i to J 90 

4.6 Roof Drainage — No gutter or rainwater pipe shall discharge 
water from one roof to another unless the discharge is from a small area 
such as a 'dormer'. For detailed information relating to the disposal of 
rain water from roofs, reference shall be made to IS : 2527-1984*. If a 
valley gutter is formed by means of sheet metal, the sheet shall be taken at 
least a distance of 300 mm under the roof on either side of the gutter. 
Near a wall the sheet metal constituting the valley gutter shall be taken 
at least 75 mm into the wall and set with cement mortar, 

4.7 Use of Glass Tiles — Glass tiles, usually of the same shape as the 
Mangalore tiles may be fixed in the same manner as other tiles at 
suitable spacing according to the requirements of roof lighting. Glass 
tiles of special types shall be laid in accordance with the instructions of 
the manufacrurers of these tiles. 



*Code of practice for fixing rain-water gutters and downpipes for roof drainage 
( revised ) . 

11 



IS : 2858 - 1984 

5. MATERIALS 

5.0 The materials used in roofing with Mangalore tiles shall conform 
to 5,1 to 5.5. 

5.1 Mortar — The mortar for use in bedding ridge tiles as well as 
Mangalore tiles shall be: 

Either composite mortar 1 : 2 : 9 ( one part cement conforming ta 
IS : 269-1976* or IS : 1489-1976t or IS : 455-1976J, two parts 
lime conforming to IS : 712-1973§ and 9 parts sand ) or lime 
mortar 1 : 3 ( one part lime conforming to IS : 7]2-i973§ and 
three parts sand ). Water used for making mortar shall 
conform to 4.3 of IS : 456.1978||. 

Water used for making mortar shall be clean and free from deleter!* 
ous materials. 

5.2 Mangalore Tiles — These shall conform to IS : 654-1 972^f. 

5.3 Ridge Tiles — These shall conform to IS : 1464-1973**. 

5.4 Ceiling Tiles — Ceiling tiles for use with Mangalore tiles {shall 
conform to IS : 1464-1973**. 

5.5 Flat Tiles — Flat tiles for use with Mangalore tiles shall have one 

of the dimensions equal to the gauge of the Mangalore tile. 

5.6 Glass Tiles — These shall preferably be of the same shapej as 
Mangalore tiles. 

5.7 Ventilating Tiles — Tiles equal in size to one plain Mangalore 
tile or two tiles laid side by side after allowing for overlapping. These 
may be used to provide top ventilation in a room. Ventilating tiles shall 
be provided wherever required at the rate of two ventilating tiles for 
every 10 m^ area of finished roof surface. A typical view of ventilating 
tiles has been shown in Fig. 5. 

5.8 Nails for Fixing Keepers — Nails used for fixing reepers or 
rafters shall be plain head nails of size 2'50 mm or 2'24 mm conforming 
to IS : 723-1972tt. The nails shall be galvanized. 

5.9 Sheet Metal for Valley Gutters — This shall be of galvanized 
metal and of thickness not less than 1*25 mm. 



♦Specification for ordinary and low heat Portland cement ( third revision ). 
fSpecification for Portland pozzolana cement ( second revision ) . 
tSpecification for Portland slag cement ( third revision ) . 
§Specification for building limes ( second revision ). 
!]Gode of practice for plain and reinforced concrete ( third revision ). 
IfSpecification for clay roofing tiles, Mangalore pattern ( second revision ). 
•♦Specification for clay ridge and ceiling tiles {first revision ). 
ttSpecification for mild steel wire nails ( second revision ). 

12 



18:2858-1984 




Fig. 5 Typical View of Ventilating Tile 



5.10 Keepers — Keepers shall be of any species of structural timber 
given in IS : 883-1970* and the size shall be in accordance with the 
design but shall in no case be less than the size as specified in 4.3. 
Keepers shall be treated for protection against decay and termites in 
accordance with IS : 401-1982t- 



5.11 Wire for Tying Down the Tile 

and shall conform to IS : 280- 1 978 J. 

6. PROGRAMMING THE WORK 



The wire shall be galvanized 



6.1 Before taking up the work of roof covering, the roof framework shall 
have been completed and the reepers nailed into position ready for 
supporting the roof covering. 



*Code of practice for use of structural timber in building ( material, grading and 
design ) ( third revision ). 

tCode of practice for preserv^ation of timber ( third revision ). 
{Specification for mild steel wire for general purposes ( third revision ). 

13 



IS: 2858 -1984 

7. PREPARATORY WORK 

?•! For Flat Tiles — Before use In the roofing, the flat tiles shall first 
be prepared by immersing in water for two hours and air-dyinj^ before 
laying. The underside of the flat tiles, may also, if so specified, be 
dipped in whitewash mixed to a creamy consistency and the tiles then 
dried. 

7.2 For Mangalore Tiles — Wherever Mangalore tiles are to be 
embedded in a mortar layer over flat tiles, the Mangalore tiles shall 
first be soaked in water for at least two hours before laying. 

8. FIXING OF REEFERS 

8.1 The reepers shall be fixed over the rafters at the specified or designed 
spacing and nailed. The nails shall penetrate at least 2 cm into the 
rafters. They shall extend at least over a length of three spans between 
the rafters. The reepers shall be nailed to the rafters by means of plain 
headed nails ( see 5.8 ). Their length shall be extended only by means of 
butt joint. The joint shall occur only over the rafters. The joints of no 
two adjacent rows of reepers shall come over the same rafter. At the 
eaves a tilting fillet shall be fixed, if necessary ( see Fig. 1 ). 

8.2 Where ceiling boards are used reapers shall be fixed in accordance 
with 4.3.1. 

9. LAYING OF MANGALORE TILES 

9.1 The tiles shall be laid from the eaves towards the ridge properly 
interlocked according to the design of the tile. The tile shall be laid 
either directly over the reepers or over an undercover ( see 9.1.1 
and 9.1.2 ). The tiles shall be laid breaking joint, that is, the left channel 
of the upper tile shall lie in the right channel of that below and shall fit 
properly one to another, the catches resting fully against battens. The 
hips and ridges of the roof shall be covered with ridge tiles which shall 
be edge-bedded in mortar ( see 5.1 ) as illustrated in Fig. 1. The mortar 
in edge bedding may be further finished with plaster or paint to match 
with the colour of the tiles. If the courses of roof tiles adjacent to the 
hip or to the ridge do not finish exactly underneath the ridge tiles, either 
purpose-made tiles or tiles cut to suitable shapes may be used. While 
finishing joints gaps in the troughs of the roof tiles giving ridge or 
hip, if large enough, shall be neatly packed watertight using small pieces 
of chips of broken tiles and mortar. At eaves the lower most course of 
the tiles shall overhang the tilting fillet by a distance sufficient to ensure 
that the water drained off from the roof discharges clear off* the eaves> 
into the gutter. 

14 



IS : 2858 - 1984 

9»1.1 Protective Measures Against Wind — A suitable arrangement shall 
foe made to secure the ends of lower most course of tiles to the roof 
structure for preventing the tiles from being blown up by wind. Al teast 
the bottom most layer of tiles, and preferably more number of layers 
above it, shall be tied to the reepers or other roof elements by means of 
galvanized wire. The tiles at the eaves shall also be protected against 
lifting by means of a galvanized steel flat of size 40 X 3 mm fixed to the 
roof as in Fig. 4. Mortar bands 200 to 250 mm wide 60 to 65 mm 
deep may also be provided over the tiled roof at a spacing of 2'5 to 3 m 
for additional protection against wind. The mortar bends shall run 
along the roof slope. 

9.1.2 Laying Mangalore Tiles Over a Flat Tile Undercover — The flat tiles 
shall first be prepared by immersing in water for tv^o hours and dried 
before laying. The underside of flat tiles shall also be dipped in white- 
wash mixed to creamy consistency and dried. The flat tile shall then be 
laid over the reeper. The mortar layer shall be spread over the flat tile 
to a thickness of not less than 25 mm. The Mangalore tile shall also be 
soaked for two hours before laying in the roof. When the mortar layer 
is spread, the soaked Mangalore tiles shall be laid so as to be fully 
embedded in the mortar over the flat tiles ( see Fig. 2 ). Where the pitch 
of the roof is more than 30*, additional fillets shall be fixed to the reepers 
at a spacing of about one metre centres, so that the flat tiles laid between 
them are retained in position ( see Fig. 2 ). The Mangalore tiles may 
also be fixed over flat tiles without mortar bedding if the work is so 
specified. 

9.1.3 Laying Mangalore Tiles Over Ceiling Tiles — Where a layer of 
ceiling tiles is to be laid as under cover the ceiling tiles shall be laid 
over the reepers and the Mangalore tiles shall be laid over them with 
appropriate interlocking between the tiles in the two layers ( see Fig, 3 ). 

9.2 Alignment — The finished slope of the roof shall be uniform ridge 
eaves. The eaves-line and the ridge-line shall, be perfectly straight, 
horizontal and parallel to each other, 

9.3 Junction Between Ridges and Hips — The joints between hip 
and ridge tiles shall be grouted so as to be leak-proof. A metal saddle 
not less than 45 cm^ area may preferably be used underneath such 

junctions as additional protection against leakage. 

9.4 Work at Valleys — Since valley is a particularly vulnerable part 
of the roof as its pitch is several degrees less than that of the general roof 
surface and it has to provide a channel for the wateY running down into 
it from two slopes on either side, special care shall be taken that a clear 
and an unobstructed channel is formed. Undercover {see 9.1.1 
and 9.1.2 ) shall be provided for the courses of tiles adjacent to the valley. 
The valley gutters shall be of galvanized steel sheet of minimum 1'25 mm 

15 



IS : 2858 - 1984 

thickness and 1*2 m wide. A 300 mm overlap shall be given at joints, 
if any, down the slope. The valley gutters shall be laid over the reepers 
and not nailed on to them from underneath. Two additional reepers of 
section 50 x 25 mm shall be fixed over the metal sheets, 150 mm away 
from the central line of the valley on either side, so as to retain the tiles 
and mortar against falling into the gutter of the valley. On either side 
of the valley, the roof shall be plastered with mortar to a thickness of 
12 mm so that rain water from the gutter is prevented from percolating 
through the tiles or the undercover to the underside of the roof ( see 
Fig. 6 ). 




VALLEY BOARD 
VALLEY RAFTER 



UNDERCOVER 



REEPERS OR 
BATTENS 



RAFTER 

GALVANIZED 
STEEL SHEET 



Fig. 6 Fixing of Valley Gutter 

10. FINISHING EDGES AROUND CHIMNEY STACKS AND 
SKYLIGHTS 

lO.I In the case of chimney stacks and other similar features, full tiles 
shall be used around them and taken into the masonry. In addition, 
metal or bitumen flashing shall be used to cover the intersection between 
the top edge of the tiling and any projection through the roof. The 
flashing shall be turned against the projection and dressed down over the 
tile. The flashing shall be well tucked into either the joints in masonry 
or grooves in concrete as the case may be and shall be wedged and 
pointed. 

11. TREATMENT OF JUNCTIONS WITH WALL 

ILl Junctions of the roof with walls shall preferably be treated for 
waterproofing in accordance with the relevant Indian Standards for 
waterproofing. Wherever special features like roof gutters and flashings 
are not provided between the junctions of the roof and wall, the tiles 
shall be let into the wall to a depth of not less than 50 mm and a drip 
moulding shall be provided at about 100 mm height above the roof 
surface, and joints between the roof and the wall shall be grouted with 
a waterproofing mortar or such other materials ( see Fig. 7 ). 

16 



IS : 2858 - 1984 



-ORtP MOULDING 



mangalore tiles 



7'5 cm 

MIN 




WOODEN 
RAFTER 



REEPERS OR 
BATTENS 



Fig, 7 Detail at the Junction of the Roof with Wall 
( Where Tiles Themselves are Used for Roof Drainage ) 

12. INSPECTION 

12.1 Inspection shall be done to avoid unsatisfactory construction which 
may result in one or more of the following defects: 



Stage Particulars of 

Inspection 



(1) _ _ (2) 

Laying of No joint between the reepers 

reapers shall occur except over the 

joist. At eaves the tilting 

fillet shall be fixed to the 

correct height. 

of Where Mangalore tiles are 

laid over flat tiles, their 
joints shall not, as far as 
possible, occur over the 
joints of the tiles. Where 
Mangalore tiles are laid as 
such over reepers, or over 
ceiling tiles, interlocking of 
tiles shall be ensured. 

17 



Laying 

tiles 



Type of Failure 
that May Occur 
if{2) is not 
Satisfactory 

. ^^^ 

Sagging or crack- 
inar 



Unsightly fall of 
roof surface near 
the eaves 



IS ! 2858 - 1984 



( Continued from page 2 ) 

Members 
Deputy C hief Engineer 

( GeNEHAIj ) SOUTHEBK RaiL 

Shki V. S. Engineer 
Shri R. L. Kumar 
Shri G, K. Majumdar 



Representing 
Railway Board ( Ministry of Railways ), New Delhi 



ShriH. S. Pasricha ( Alternate) 



Indian Institute of Architects, Bombay 
Institution of Surveyors, New Delhi 
Hindustan Prefab Ltd, New Delhi 



Shri B. V. B. Pai 

Srri p. Srinivasan { 
Shri R. Rajappa 
Dr M. Ramaiah 



Alternate ] 



Shri Z. Gkorge ( Alternate ) 
Senior Deputy Chief Ejjgi- 
NEEB ( Bldgs ) 
Executive Engineer 
( Planning ) ( Alternate ) 
Shri K. S. Srinivasan 

Shbi Sashi Kant ( Alternate ) 
Superintending Engineer 

(B&R) 
Surveyor ov Works, Madras 
Centre Circle 



Concrete Association of India, Bombay 

) 

Tata Consulting Engineers, Bombay 
Structural Engineering Research Centre ( CSIR ), 
Madras 



Public Works Department, 
Nadu, Madras 



Government of Tamil 



National Buildings Organization, New Delhi 

Public Works Department, Government of Andhra 

Pradesh, Hyderabad 
Central Public Works Department, New Delhi 



18 



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